Question

A 0.72-mol sample of PCl5 is put into a 1.00-L vessel and heated. At equilibrium, the vessel contains 0.40 mol of PCl3(g) and 0.40 mol of Cl2(g). Calculate the value of the equilibrium constant for the decomposition of PCl5 to PCl3 and Cl2 at this temperature.

a) 0.56
b) 0.78
c) 1.00
d) 1.44

Answer 1

The equilibrium constant for the decomposition of PCl5 to PCl3 and Cl2 at this temperature is 0.2222.

Step-by-step explanation:

The equilibrium constant, Kc, for the decomposition of a sample of PCl5 to PCl3 and Cl2 can be calculated using the concentrations of the products and reactants at equilibrium. In this case, the vessel initially contains 0.72 moles of PCl5 and at equilibrium, it contains 0.40 moles of PCl3 and 0.40 moles of Cl2.

The equilibrium constant is calculated by taking the ratio of the products' concentrations to the reactant's concentration, each raised to their respective stoichiometric coefficients. Therefore, Kc = ([PCl3] * [Cl2]) / [PCl5] = (0.40 * 0.40) / 0.72 = 0.2222.